Soybean-Boosting Bug Enjoys Agronomic Success as New Inoculant

A nitrogen-fixing bacterium developed by
Agricultural Research Service
scientists can boost farmers' soybean yields while reducing their
reliance on commercial fertilizer. That's the latest report from
Urbana Laboratories, a Missouri company with an exclusive license from
ARS to market the new Bradyrhizobium japonicum strain as an
inoculant for soybean seeds.

ARS researchers originally developed, tested and patented the strain
in 1991 as an improvement over existing Bradyrhizobium
bacteria sold commercially to farmers. This family of soil-dwelling
microbes "fixes," or converts, atmospheric nitrogen into a
chemical form that soybean plants can use for optimal growth and
higher yield. The soybean plant offers the bacteria "room and
board" in its roots.

Field studies by the ARS researchers showed their new B.
japonicum strain outmatched a top performing bacterial strain by
forming 44 percent more nitrogen-fixing nodules on the plants' roots.
This is a boon because farmers can apply less artificial fertilizer,
reducing their production costs and the chance of groundwater
contamination.

Urbana licensed the ARS strain in 1994 and developed inoculant
products for sale to farmers the following year. Results from more
than 100 field trials in 11 states indicate use of the bacterium
boosts yields by an average of 3.5 percent. This can translate to an
extra two bushels per acre for the farmer.

Urbana estimates its inoculants containing the new strain have been
used on 1.2 million acres of soybeans since 1995, the first year of
sales. The bacterium's agricultural success is also the culmination of
a 15-year research project that the ARS scientists concluded this
fall.